Roller grinding mill and control therefor



22, i967 R. M. WILLIAMS 33331142 ROLLER GRINDING MILL AND CONTROL THEREFOR Filed Aug. 3, 1964 Sheets-Sheet l 8 I 80 72 76 71 75 n T 34 29 81 34 31 2 31 I v I I I L 1 H 30 39 3o l -1 27 i 3 22 23 O 22 26 41 23 11 O O 24. 21-- 11 46 FTC! I 45 v INVENTOR ROBERT M. WILLIAMS BY ATTORNEYS 1967 R. M. WILLIAMS 3,337,142

ROLLER GRINDING MILL AND CONTROL THEREFOR Filed Aug. 5, 1964 5 Sheets-Sheet 2 28 26 INVENTOR FIG 3 I ROBERT M. WILLIAMS BY ,M; 4/

ATTORNEYS Aug- 22, 1967 R. M. WILLIAMS ROLLER GRINDING MILL AND CONTROL THEREFOR Filed Aug.

3 Sheets-Sheet 5 25o PSIG.

FIG. 9

w w B 87 INVENTOR ROBERT M. WILLIAMS FIG. 8

ATTOR NEYS United States Patent a corporation of Missouri Filed Aug. 3, 1964, Ser. No. 386,977 Claims. (Cl. 241-130) This invention relates to roller grinding mill apparatus for comminuting solid materials such as mineral products, pigments, insecticides, clays or metal granules.

In the present mill, the arrangement of operating parts has been greatly simplified and organized so that control over the grinding of materials can be obtained in a positive manner, not by speed adjustment but by not allowing the pressure of the rolls revolving at any given speed against the bull ring to increase the value where there is a breakdown of the flow of material into the grinding zone.

It is, therefore, an object of this invention to provide an improved roller mill which is controllable to have optimum feed conditions and which can be regulated to produce materials from micron size upwards.

It is also an object of this invention to provide simply constructed control means for roller mills, whereby the same can be incorporated as original equipment or can be applied to existing mills with minimum cost.

A further object of this invention is to provide control means of fluid pressure type for application to roller mills in which the roller arms are pivoted for centrifugal response and to apply the control means for resisting the centrifugal forces at higher speeds or for complementing such forces at lower speeds, thereby affording a wider range of comminuting action than is possible at the present timewith existing mills.

Another object of the present invention is to improve the comminuting action of roller mills so that greater production is obtainable with a quiet grinding action.

Yet another object of the invention is to provide an improved roller mill in which the pressure of the grinding rolls can be closely controlled to grind in the micron range without noise or vibration and with no skipping or jumping.

In its essential arrangement the roller grinding mill of this invention includes an annular grinding ring (usually called bull ring), a central rotating member, and a plurality of grinding roll assemblies pivotally hung from the central rotating member so as to move outwardly toward the bull ring under the influence of centrifugal force. The roll assemblies have portions extending above the pivot axes, and the improved control means of this invention is assembled between the upwardly extending portions and the rotating central member so as to be effective in the revolving system of parts of the apparatus. One control means may be of the fluid pressure type which not only serves to regulate the roll pressure on the bull ring, but can be eflectively applied to guard certain bearings in the system against contamination by the fine materials being processed. The control means includes pressure regulation of motor means for each roll assembly, and supply of the pressure fluid through an improved rotary union or swivel which provides a reservoir of suflicient capacity to render the motor means effective to function as dampers for the roll assemblies.

In a roller grinding mill of the type hereinafter to be described, optimum feed conditions depend, to a large extent, upon the speed of rotation of the rotating system of rollers. If the outward pressure of the rolls is decreased the speed of the mill can be increased, and by so doing the output of the mill per unit of time can be increased. On the other hand, if the speed of the mill is reduced and the roll pressure increased just enough to prevent bouncing or skidding of the rolls on the material, the mill can be used to produce micron size outputs. Furthermore, regulation of the pressure fluid supply through a reservoir or supply chamber common to all motor means can give precise control over roll pressures, and can serve to damp out objectionable bouncing and oscillations of the roll assemblieswhich, if uncontrolled, can Wreck the apparatus.

Other objects and advantages will appear as certain preferred embodiments of the invention are set forth in the following specification and with reference to the accompanying drawings, wherein:

FIG. 1 is a vertical sectional view of a roller mill constructed in accordance with the invention;

FIG. 2 is a greately enlarged fragmentary sectional view of the roller mill shown in FIG. 1, but with certain modifications added thereto;

FIG. 3 is a fragmentary sectional View of a modification of the invention;

FIG. 4 is a fragmentary plan view taken at line 4-4 in FIG. 2;

FIG. 5 is a detail sectional view at line 55 in FIG. 2;

FIG. 6 is a diagrammatic layout of the fluid pressure system as applied to the mill seen in FIG. 1;

G. 7 is a greatly enlarged vertical section of the principal fluid pressure head attachment for the roller mills of either FIG. 1 or FIG. 2;

FIG. 8 is a fragmentary sectional view taken at line 88 in FIG. 7; and

FIG. 9 is a diagrammatic layout of a fluid pressure control system for the roller mills of the invention.

Wherever possible, like parts will be designated by like numerals of reference throughout the drawings.

In FIG. 1 of the drawings the roller mill has been shown in vertical section with a part of the structure omitted so that the essential features of the invention can be seen and appreciated. A main frame part 10 has a mounting flange 11 for its support on parts not shown. The frame 10 has a frusto-conical or tapered inner wall 12 which carries a stationary grinding or bull ring 13 press fitted into position. The frame 10 is closed at its bottom by an inwardly directed flange 14- of annular form in which the central aperture forms a'seat for the base 15 of a vertical tubular column 16. Thebase 15 and flange 14 together form the bottom of the frame 10 and provide a retainer for the material falling through the zone of the grinding action. A cylindrical housing 18 is mounted on the frame 10 to extend upwardly above the frame and enclose certain parts of the mill to be described. The housing carries a feed inlet 19 of automatic type having its discharge 20 opening to the grinding zone defined by the bull ring 13. The material to be ground in the mill falls through the zone of the bull ring 13 into the bottom and is constantly thrown back to the bull ring by the plows 21. Concurrently air is fed through the radial passages 22 in the sides of the frame 10. The passages open between vertical partitions or vanes 23 integral with frame 10, and each vane 23 is provided with a liner 24. A combination of the action of plows 21, there being a plow for each roller although only one is shown, and the air under pressure fed to passages 22 will constantly agitate the material upwardly into the grinding zone. As the particles are reduced to proper size the air will sweep the same upwardly through housing 18 and float the particles into an air separator (not shown) where the fines pass on out of the apparatus and the larger particles drop back to the grinding zone.

The base 15 carries a bearing 25 for a vertical drive shaft 26 which extends up in the column 16 and is sup:

ported by a sleeve bearing 27. The shaft projects above the top -of the column 16 to support a head member 28 held in place by a nut 29. The head 28 has radially extending arms 30 equal in number to the number of rollers to be used. In the present apparatus five rollers are used, as is indicated in FIGS. 4 and 6, but the view in FIG. 1 shows only two for convenience of illustration. Each arm 30 is split and adapted to support a horizontally positioned pivot pin 31 which is used to support the upper member 32 of the roller hanger 33. The member 32 carries a shaft 34 which extends down inside the hanger assembly 33 (see FIG. 2) and near the lower end of the shaft (not shown) is a thrust hearing which takes the load axially along the shaft. In operation the outer sleeve 35 of the assembly 33 is free to rotate about the vertical axis of shaft 34 and a roller grinder 36 is fixed at the lower end of sleeve 35. The shaft 34 is held in position by a special elongated cap nut or extension means 37 which has a bifurcated upper end 38.

The head member 28 also supports a sleeve 40 at its upper bell end 39. The sleeve encases the column 16 and at its lower end flares outwardly at 41 to form a support for the plows 21, only one being shown. The flared end 41 accommodates the enlargement on the column 16 for the bearing 15 carrying the center shaft 26. The lower end 42 of the shaft 26 carries a gear 43 which is driven by the gear 44 on the power input shaft 45 from a suitable prime mover (not shown). The shaft 45 is carried in bearings 46 on a bracket 47 attached to the flange 11 of frame 10. The gears 43 and 44 are enclosed in a housing 48. The power input to shaft 45 drives shaft 26 and head 28 so that the hanger assemblies 33 pivot on pins 31 (like the weighted arms of a centrifugal govvernor) and rollers 36 bear in free rolling relation upon the bull ring 13. The speed of rotation of head 28 causes the rollers 36 to hear more forcefully on the ring 13, as the square of the speed, so that speed adjustment is required to prevent the roller pressure at the ring 13 from exceeding a valve that will cause roller skid and complete breakdown of material between the grinding surfaces and allow metal-to-metal contact. Various ways have been suggested to limit the roller pressure, but each has been either too expensive, fraught with problems of maintenance, or inadequate to do the job required.

Still referring to FIG. 1, and to other views as required, it is seen that the center shaft 26 projects upwardly beyond head 28 and nut 29 so that a chambered support member 49 may be threaded down on the projecting end. The member 49 has projecting cars 50 (FIG. 4) to be engaged by complementary bifurcated ears 51 on the inner ends of the fluid motors 52. It is preferred to use piston-cylinder motors in which the inner ends are pivoted on pins 53 between cars 51 on the cylinders and ears 50 on member 49. The outer ends of the fluid motors 52 are arranged with the movable piston rods 54 projecting therefrom and into pivoted connection at pins 55 in the bifurcated upper ends 38 of the cap nuts 37 (FIG. Each fluid motor 52 has its fluid pressure responsive piston 56 (FIG. 2) connected to the inner end of rod 54 so that relative movement between the pistons and cylinders will cause movement of the extension means 37 and swing the hanger assemblies 33 about pivots 31.

The fluid under pressure is supplied through a rotary or swivel union 57 (FIG. 7) of air seal type. The union 57 includes a primary element or center mandrel 58 having an axial bore forming a main passage 59 open from top to bottom. The mandrel 58 is formed with an enlarged lower end 60 having a threaded portion 61 which screws into the upper end of member 49. Adjacent the center bore 59, there are provided five parallel side bores forming secondary passages 62 (FIG. 8) which extend upwardly in the mandrel 58 to a smaller diameter portion where the bores break out laterally to form outlets 63. The lower ends of bores 62 are closed by plugs 64, and spaced above the plugs. The mandrel is formed with lateral tapped inlet connections 65 opening to bores 62. The mandrel 58 rotates with the shaft 26 on which it is mounted, while the enclosure for the union remains stationary. Thus, the secondary element or outer casing 66 is carried on a sleeve bearing 67 having a close running fit with the mandrel. The bearing 67 is fitted into a backing element 68 which is sealed at O ring 69 and held by a snap-lock element 70. The casing 66 is formed with a threaded socket 71 to receive a pressure fluid supply conduit 72. The casing 66 also has an upper threaded nipple 73 which supports a high pressure magnetic type seal 74 and an elbow 75 for the connection of a pressure fluid supply conduit 76. The conduits 72 and 76 connect with other conduits 77 and 78, respectively, through flexible members 79 and- 80, whereby the conduits 77 and 78 may be extended through the side of casing 18 without causing excessive vibration in the rotary union 57.

Turning now to FIG. 6, and using reference numerals from FIGS. 1 and 7 where applicable, it is understood that high pressure fluid is supplied in conduit 76 and low pressure fluid is supplied in conduit 72. The high pressure fluid passes through bore 59 in mandrel 58 to the chamber or reservoir 49a in member 49 and thence into each of five flexible hoses 81 which connect with the motors 52. The low pressure fluid supplied in conduit 72 passes to casing 66 where it may be met by the pressure fluid exhausted from motors 52 at flexible hoses 82 which latter fluid enters the mandrel (FIG.v 7) 58 at ports 65 and passes upwardly in bores 62 to the casing 66. The fluid exhausted at conduits 82 is low pressure, though it may exceed the pressure in conduit 72. When combined in the casing 66 with the low pressure fluid supply at conduit 72, the pressure fluid is exhausted to housing 18 through the clearance space in bearing 67, thus continuously sweeping the bearing free of abrasive material. It should be remembered that the space around the member 49 is in an abrasive and contaminating atmosphere due to the forced flow of finely ground material and air upwardly in the apparatus and out at the top of housing 18.

In FIG. 9 the high pressure fluid is supplied from a suitable compressor 83 through a filter 84 to a regulator 85 and to conduit 78. The fluid pressure is monitored by gauge 96 on regulator 85. The low pressure fluid is supplied from a suitable blower 86 equipped with a silencer 87 and a pop-01f device 88 to a flow restricting valve 89 and conduit 77 in which a pressure gauge 90 is used. The valve 89 restricts back flow in lines 77 and back to lines 82 and thereby provides a damping force against pistons 56. The system of FIG. 9 furnishes the control over pressure fluid to cylinders 52 for pushing outwardly on the extensions 37 above pivot pins 31 to oppose the centrifugal force developed by the rotating system of rollers 36. By selecting the right pressure valve for the fluid the pressure of the rollers 36 on the surface of the bull ring 13 can be regulated for optimum grinding efficiency.

Let it be assumed that optimum grinding conditions are obtained for the character of material being processed. The grinding rolls 36 will normally maintain a stable position relative to bull ring 13, but should a particle of abnormal hardness pass under a roll 36 it will force that roll inwardly against centrifugal force, or it may cause the roll to skip or bounce which will upset the balance of the mill. The roll bounce sets up an oscillation which, if unchecked, can be destructive, but the motor means 52 controlling the bouncing roll 36 acts, as a damper because the fluid suddenly forced out conduit 82 (FIGS. 1, 6 and 9) tends to reverse the flow in conduits 72 and 77. However, reverse flow in conduit 77 is checked by the restriction valve 89. Concurrently, the piston 56, attempting to increase the exhaust pressure in conduit 82, will tend to draw high pressure fluid from the reservoir 49a in member 49. The effect of this double action is to constantly monitor the position of piston 56 and damp out rapid oscillations which checks the oscillations of the grinding roll 36 that started the described chain of events. Since the reservoir 49a has a large volume relative to each chamber for pistons 56, the momentary oscillation of any given piston 56 will have little effect on other pistons so that the stability of the system of rotating grinding rolls 36 is maintained and the output efliciency of the apparatus is not appreciably upset. It is preferred to use air as the pressure fluid, as it will compress and act as a cushioning medium. The air also can be used to keep certain bearings clear of the material being processed, which bearings heretofore became bound up after a short period of exposure to the dust laden air flowing in casing 18.

In FIG. 2 a modification includes the installation of a T-connection 91 in the exhaust from each motor 52, one side of the T is for hose 82, and the other side is for a hose 92 which leads to a connection 93 leading into a passage 94 around a seal 94a above the bearing 94b in the hanger '33 for each roller 36. The positive supply of air at connection 93 continuously sweeps through the passage 94 and prevents fines from entering to cause rapid wear in the bearing and seal.

In FIG. 3, an alternate arrangement is shown in which the high and low pressure fluid hoses are reversed from that shown in FIG. 1. In the alternate view high pressure hose 81a is connected to the outer end of motor 52 to drive the piston 56 inwardly and add the motor force to the centrifugal force on roller 36. The exhaust from motor 52 is now by way of hose 82a to the mandrel 60 of the rotary union 57.

In operation, the apparatus is set to run at optimum feed conditions which, to a large extent, depends upon the speed of rotation of the rotating assembly 2-6, 28, 30, 33 and rolls 36. By adjusting the regulator 85, monitored by the gauge 96, the pressure of rolls 36 can be set so that the speed of shaft 26 can be increased to the point where the output of the mill per unit of time can be increased. The roller mill of FIGS. 1 and 2 have the pressure fluid motors 52 arranged to offset the centrifugal force acting on the rollers to force the rollers 36 inwardly. The roller pressure at the bull ring due to centrifugal force is not carried up to the point where no material can form a liner between the grinding surfaces. If the operator changes material without adjusting the control, the material may not be able to sustain roll pressure so that the mill develops a tremendous roar and sets up vibration due to metal-to-metal contact, but at the optimum pressure the correct amount of material is permitted between the grinding surfaces and the mill has a quiet action with relatively very little vibration and abrasive wear. Also, area of contact of the material between the rollers 36 and bull ring 13 is maintained because the rollers do not bounce and skip and this allows higher speeds for greater output. It has been pointed out that prevention of roll bounce and skip on the bull ring 13 is through the damping action of the motors 52 since these motors 52 are on the opposite side of the pivots 31 from rolls '36 and tend to oppose the roll action.

Without the motors 52, the upper speed range is limited as the pressure varies as the square of the speed, and higher speeds merely prevent material from forming a liner between the bull ring 13 and rollers 36. A benefit obtained by the motors 52 is that the degree of fineness of the output product con be controlled by the setting of regulator 85. The design of the member 49 and the assembly of motors 52 thereon makes it possible to install the same on existing mills. As the mill parts operate in extremely fine dust-laden atmosphere the bearings, joints and moving parts are constantly contaminated with abrasive substances, but by using the low pressure fluid as shown the bearings and joints can be air purged. When the rotating system reacts to expel the air from motors 52 back to the union 57 against the low pressure fluid systern, the low pressure system is protected by the pop-off valve 88 to relieve the back pressure on blower 86 if the flow restriction valve 89 is not set properly. As may be seen in FIGS. 1, 2 and 3, each motor rod 54 is provided with a flexible boot 95, thus sealing the motors against internal contamination.

The modification of FIG. 3 applies the force of motors S2 additively with the centrifugal force developed by the rollers 36. This system is useful for extra fine grinding at low speeds. Most'systems contemplate the use of the system shown in FIGS. 1 and 2, and in FIG. 9 the regulator is provided with a gauge 96 so that the mill operator can select the pressure best suited to the grind wanted. The gauge 96 permits the operator to monitor the mill operation.

In a system of the character disclosed it is a great advantage to be able to activate the pressure fluid system and withdraw the rolls 36 from the bull ring 13. This will reduce drag when starting up the mill as centrifugal force would normally move the rolls out to ride on the ring while coming up to speed. The starting power will be reduced and the blower system connected to the passages 22, together with the plows 21, will be given a chance to agitate the material in the bottom of the frame and establish a liner at the bull ring for the rolls to work on and to reduce the metal-to-metal contact.

While the disclosure has been given with a roller mill having five rollers 36, it is understood that more or fewer rollers can be employed. It is also understood that the invention is not to be limited to the precise details herein illustrated and described since the same can be carried in other ways consistent with the scope of the invention as claimed.

What is claimed is: 3

1. The combination in a material pulverizing mill of: a fixed grinding member; a plurality of grinding rolls; elongated hanger means, each including an outer sleeve having an upper open end and connected at a lower end to a grinding roll, an inner supporting shaft for each outer sleeve having one end engaged within said outer sleeve and an opposite end extending above the upper open end of said outer sleeve, a pivot member on said opposite end of each said supporting shaft to close the upper open end of said outer sleeve, and an extension element projecting above each pivot member; head means to support each hanger means including pivots engaged with each pivot member in position to normally locate said grinding rolls pendently adjacent said fixed grinding member; drive shaft means connected to said head means to rotate the same about a fixed axis and cause said hanger means to swing in a direction radially of said fixed axis of rotation and move said grinding rolls into said grinding member; individual pressure fluid responsive position control means between said drive shaft and each extension element to substantially fix the radial distance from said .fixed axis of rotation to each of said extension elements and, hence, the position of said grinding rolls relative to said fixed grinding member; and a pressure fluid system including high pressure supply and low pressure supply means connected to opposite sides of said control means, regulator means in said high pressure sup ply and flow restriction means in said low pressure supply, said regulator means being selectively settable for a given radial distance, and said flow restriction means damping roll action to change the radial distance.

2. Roller grin-ding mill apparatus for comminuting solid materials comprising a fixed bull ring having a grinding surface, circularly spaced grinding rolls disposed adjacent said grinding surface of the bull ring, circularly spaced hanger means having pivot axes intermediate the ends thereof, a grinding roll mounted on one end of each said hanger means, a drive shaft connected to said hanger means at said pivot axes to rotate said hanger means and simultaneously rotate said grinding rolls in an orbit causing said rolls to swing into grinding relation with said grinding surface, means connected to said drive shaft and located inwardly of the circularly spaced hanger means and spaced from the opposite ends of said hanger means, pressure fluid responsive motor means connected between said last means and each of said opposite ends of said hanger means, said last means including a reservoir chamber for pressure fluid, union means connected to said last means and formed with a primary passage open to said reservoir chamber and with secondary passage adjacent said primary passage, a high pressure fluid supply system connected into said union means to supply high pressure fluid into said reservoir chamber, a low pressure fluid supply system connected into said union means in communication with said secondary passages, primary conduits connected from said reservoir chamber to said motor means, and secondary conduits connected from said motor means to said secondary passages, said high pressure fluid activating said motor means to simultaneously position said grinding rolls relative to said grinding surface and said low pressure fluid stabilizing the action of said motor means.

3. The roller grinding mill apparatus set forth in claim 2 wherein said high pressure fluid supply system includes regulator means to control the activation of said motor means in relation to the rotary speed of said drive shaft.

4. The roller grinding mill apparatus set forth in claim 3 wherein said high pressure fluid supply system also includes gauge means to visually monitor the pressure of pressure fluid supplied to said motor means, said gauge means being connected to said regulator means.

5. The roller grinding mill apparatus set forth in claim 2 wherein said low pressure fluid supply system includes a flow restriction device to restrict the back pressure in said low pressure system.

6. Roller grinding mill apparatus for comminuting solid materials comprising a bull ring in fixed position, grinding rolls inwardly adjacent said bull ring, pivoted hanger means supporting each said grinding roll from pivot axes spaced to one side of said bull ring, a common drive shaft connected to said pivot means adjacent the pivot axes, extension means on said pivoted hanger means projecting away from said grinding rolls, a reservoir member carried by said drive shaft centrally adjacent said extension means, pressure fluid motor means connected to said reservoir member and to each of said extension means, a rotary union carried by said reservoir member and including a mandrel fixed to said member to rotate therewith and a non-rotating casing bearinged upon said mandrel, said mandrel having a main passage open to said reservoir member and secondary passages open to said casing, said casing having main and secondary inlets respectively communicating with said main and secondary passages, first conduit means connected from said reservoir member to one side of each motor means, second conduit means connected from the opposite side of said motor means to said secondary passages, and a pressure fluid supply system having a high pressure fluid supply connected into said main casing inlet to supply said reservoir member, a low pressure fluid supply connected into said secondary casing inlet, and means in said system to regulate the grinding action of said grinding rolls relative to said bull ring.

7. In roller grinding mill apparatus having a fixed bull ring, a plurality of circularly spaced grinding rolls adjacent said bull ring, hanger means connected to each of said grinding rolls adjacent the lower ends thereof, head means pivotally connected to each of said hanger means above the lower ends thereof and below the upper ends, a drive shaft connected to rotate said head means whereby said grinding rolls swing radially outwardly about the pivot connections and the upper end of each of said hanger means moves radially inwardly, the improvement of a chambered member mounted adjacent said head means to rotate therewith, piston-cylinder means operatively connected to each of said hanger means adjacent the upper ends thereof and to said chambered member, a mandrel element carried by said chambered member and formed with a main passage open to said chambered member and a journal on the exterior of said mandrel element, a casing having a first inlet communicating with said main passage and having a second inlet open to an interior space, a bearing in said casing interior space, said casing space enclosing a portion of said mandrel element with said bearing on said journal, conduit means connected between said chambered member and one side of each of said piston-cylinder means, said first of said casing inlets communicating with said main mandrel passage, a high pressure fluid supply system connected to said first casing inlet to supply high pressure fluid to each of said conduit means, and a low pressure fluid supply system connected to said second casing inlet to supply low pressure fluid to said bearing for flushing said bearing.

8. The improvement set forth in claim 7, wherein said mandrel element is formed with secondary passages opening to said interior space, and other conduit means are connected from said secondary passages to the opposite side of said piston-cylinder means, said other conduit means directing the exhaust from said piston-cylinder means into said casing interior to mingle with said low pressure fluid.

9. In roller grinding mill apparatus having a fixed bull ring, a plurality of circularly spaced grinding rolls adjacent said bull ring, hanger means connected to each of said grinding rolls adjacent the lower ends thereof, head means pivotally connected to each of said hanger means above the lower ends thereof and below the upper ends, a drive shaft connected to rotate said head means whereby said grinding rolls swing radially outwardly about the pivot connections and the upper end of each of said hanger means moves radially inwardly, the improvement of a chambered member mounted on said head means to rotate therewith, cylinder means pivotally connected at inner ends to said chambered member, a piston and rod carried by each cylinder, said rods extending through the outer cylinder ends and connected to said hanger means adjacent the upper ends thereof, first conduits connecting one of the ends of said cylinder means and said chambered member, a primary element carried by and communicating with said chambered member, a secondary element bearing upon and enclosing a part of said primary element, passage means in said primary element opening into said secondary element, second conduits connecting the other of the ends of said cylinder means and said passage means in said primary element, said primary element being rot-ational with said chambered member and said secondary element being normally non-rotary, a high pressure fluid supply system connected into said secondary element to supply fluid to said primary element, a low pressure fluid supply system connected into said secondary element to supply fluid thereto about said primary element, and seal means in said secondary element separating said high and low pressure fluid, said low pressure fluid supplied to said secondary element passing through said bearing between said primary and secondary elements.

10. The combination in a material pulverizing mill of: a fixed grinding member; a plurality of grinding rolls adjacent said fixed grinding member; elongated hanger means for each grinding roll, each hanger means including an outer sleeve connected adjacent its lower end to a roll and having an upper open end, an inner supporting shaft having one end extending above said outer sleeve, seal means between said outer sleeve and said inner shaft adjacent the upper open end of said outer sleeve, a member on said one end of each inner shaft having a portion closing the upper open end of said outer sleeve and an extension element projecting thereabove; means on said member to support each hanger means in a normally pendent position with said grinding roll adjacent said fixed grinding member; drive shaft means connected to said support means to rotate the same and rotate said hanger means,- said grinding rolls engaging said grinding member and high pressure fluid for all said fluid motors, first individual 10 high pressure fluid conduits connecting said union means and each fluid motor, a low pressure fluid supply system connected to said union means, and second individual low pressure fluid conduits connecting said union means and each of said seal means.

References Cited UNITED STATES PATENTS 557,529 3/1896 Holland 241132 2,610,802 9/1952 McIlvaine 241133 X 2,909,330 10/1959 Hardinge 241118 X ANDREW R. JUHASZ, Primary Examiner. 

1. THE COMBINATION IN A MATERIAL PULVERIZING MILL OF: A FIXED GRINDING MEMBER; A PLURALITY OF GRINDING ROLLS; ELONGATED HANGER MEANS, EACH INCLUDING AN OUTER SLEEVE HAVING AN UPPER OPEN END AND CONNECTED AT A LOWER END TO A GRINDING ROLL, AN INNER SUPPORTING SHAFT FOR EACH OUTER SLEEVE HAVING ONE END ENGAGED WITHIN SAID OUTER SLEEVE AND AN OPPOSITE END EXTENDING ABOVE THE UPPER OPEN END OF SAID OUTER SLEEVE, A PIVOT MEMBER ON SAID OPPOSITE END OF EACH SAID SUPPORTING SHAFT TO CLOSE THE UPPER OPEN END OF SAID OUTER SLEEVE, AND AN EXTENSION ELEMENT PROJECTING ABOVE EACH PIVOT MEMBER; HEAD MEANS TO SUPPORT EACH HANGER MEANS INCLUDING PIVOTS ENGAGED WITH EACH PIVOT MEMBER IN POSITION TO NORMALLY LOCATE SAID GRINDING ROLLS PENDENTLY ADJACENT SAID FIXED GRINDING MEMBER; DRIVE SHAFT MEANS CONNECTED TO SAID HEAD MEANS TO ROTATE THE SAME ABOUT A FIXED AXIS AND CAUSE SAID HANGER MEANS TO SWING IN A DIRECTION RADIALLY OF SAID FIXED AXIS OF ROTATION AND MOVE SAID GRINDING ROLLS INTO SAID GRINDING MEMBER; INDIVIDUAL PRESSURE FLUID RESPONSIVE POSITION CONTROL MEANS BETWEEN SAID DRIVE SHAFT AND EACH EXTENSION ELEMENT TO SUBSTANTIALLY FIX THE RADIAL DISTANCE FROM SAID FIXED AXIS OF ROTATION TO EACH OF SAID EXTENSION ELEMENTS AND, HENCE, THE POSITION OF SAID GRINDING ROLLS RELATIVE TO SAID FIXED GRINDING MEMBER; AND A PRESSURE FLUID SYSTEM INCLUDING HIGH PRESSURE SUPPLY AND LOW PRESURE SUPPLY MEANS CONNECTED TO OPPOSITE SIDES OF SAID CONTROL MEANS, REGULATOR MEANS IN SAID HIGH PRESSURE SUPPLY AND FLOW RESTRICTION MEANS IN SAID LOW PRESSURE SUPPLY, SAID REGULATOR MEANS BEING SELECTIVELY SETTABLE FOR GIVEN RADIAL DISTANCE, AND SAID FLOW RESTRICTION MEANS DAMPING ROLL ACTION TO CHANGE THE RADIAL DISTANCE. 